The invention relates, in particular, to products such as metallic strips or sections and, in particular, in the form of an alloy.
This applies in particular to tin bronze which, as cast, contains, in addition to the solid solution .alpha., the phases .beta. and *.
Various processes exist for homogenizing and recrystallizing tin bronze.
The most commonly used process consists in placing the metal coils, which are as cast, in an in-and-out furnace and bringing their temperature to about 700.degree. C. over a period sufficiently long to ensure that no point of the metal exceeds certain critical temperatures (remelting of phases) and in maintaining this temperature for a sufficiently long time to ensure that the phases to be eliminated have disappeared: this cycle is very long: twenty-four hours for example.
It is likewise known that the metal as cast can be cold-worked in order to reduce the treatment time and improve homogenization. This cold-working ffects the whole of the cast product and is reflected in a significant reduction in thickness, reducing for example a strip of 15 millimeters to 10 millimeters.
By virtue of the cold working, the treatment time is reduced but the rolling which accomplishes the cold working of the metal and the roll bending for coiling the product increase the risk of creating defects in the metal since the phases which are still present in the metal and which it is the intention to eliminate by the homogenization treatment increase the brittleness of the metal.
The two processes above are discontinuous processes since the installation used to carry out the homogenization is not placed in line with the casting installation.
There is a third process for carrying out an in-line homogenization. Thus the product does not pass into a furnace in the form of a coil but in the flat. For this, a furnace of a certain length placed directly at the outlet of the continuous casting installation is required. The disadvantage of this process is that it results in considerable furnace lengths; the advantage is that this process avoids cold shut and reduces the risk of creating roll bending defects since the roll bending of the products, for example to coil them, is not carried out until after the treatment, when the product is sufficiently homogeneous.
In conclusion, none of the above processes permits appreciable modification of the crystallographic structure of the alloy, which remains a structure as cast.